Bisaminophenyl-based curatives and amidine-based curatives and cure accelerators for perfluoroelastomeric compositions

ABSTRACT

Novel monoamidine, monoamidoxime and bisamidine curatives, co-curatives and cure accelerators are provided for use with perfluoroelastomeric compositions as well as novel synthesis methods for making monoamidine- and monoamidoxime-based curatives, co-curatives and cure accelerators. Also provided are diphenyl-based curatives, co-curatives and cure accelerators having sufficiently high molecular weight such that the melting temperature of the curatives, co-curatives and cure accelerators is no greater than about 240° C., and more preferably no greater than about 230° C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. 119(e) of U.S.Provisional Application No. 60/443,744, filed Jan. 29, 2003.

BACKGROUND OF THE INVENTION

Fluoroelastomers, and more particularly, perfluoroelastomers arematerials known for their high levels of chemical resistance, plasmaresistance, acceptable compression set resistance and satisfactorymechanical properties. Fluoroelastomers have thus found use as seals,gaskets and linings. When high temperature or aggressive or harshenvironments, such as corrosive fluids, solvents, lubricants, andoxidizing or reducing conditions are implicated, perfluoroelastomers arethe materials of choice. Fluoroelastomers are made by various routesusing fluorinated monomers. Perfluoroelastomers are typically formed byusing perfluorinated monomers, including a perfluorinated curesitemonomer, polymerizing the monomers and curing (cross-linking) thecomposition using a curing agent which reacts with the incorporatedcuresite monomer to form a material which exhibits elastomericproperties. Suitable curesite monomers include, among others, thosehaving cyano curesites. Examples of primary and secondarycyano-containing curesite monomers are known in the art. It is believedthat in curesite monomers having cyano curesites, certain curing agentstrimerize the cyano cure sites which join to form triazines.

Known curing agents include organometallic compounds and the hydroxidesthereof, especially organotin compounds, including allyl-, propargyl-,triphenyl- and allenyl tin and the hydroxides. The tetraalkyltincompounds or tetraaryltin compounds, for example tetraphenyltin, arecommon. However, these curing agents provide a relatively slow rate ofcure, are toxic and can introduce metallic contaminants to resultingelastomers.

Curing agents containing amino groups have also been employed.Bisaminophenols, bisaminothiophenols and bisamidrazones are additionaltypes of curing agents. Those having a diphenyl structure havingsubstitutions on each phenyl ring of amino and hydroxyl, diamine, andamino and thio are generally known in the art as being connected bystructures including: —SO₂—, —O—, —CO—, alkyl groups of 1-6 carbonatoms, and a carbon-carbon double bond. While perfluoroalkyl groups of1-10 carbon atoms have been loosely described, actual synthesis and useof such compounds as curatives have not been demonstrated. Thosediphenyl structure type materials which are in use and have knownsyntheses, are primarily compounds which have three carbon alkyl groupsand in which the phenyl groups are attached to the central (second)carbon in the bis- position. For example, the most well known curativeof this type is 2,2-bis[3-amino-4-hydroxyphenyl] hexafluoropropane, alsoknown as diaminobisphenol AF or BOAP.

BOAP is a crystalline solid with a melting point of about 245-248° C.BOAP is not very compatible with perfluoroelastomers, is difficult todisperse rapidly and uniformly with perfluoroelastomers, and is thus arelatively slow-acting curative.

R. C. Evers, J. Polym. Sci. 16, 2833-2848 (1978) describe use offluorocarbon ether bisaminophenols as monomers for making fluorocarbonether-bibenzoxazole polymers. Evers outlined a synthesis route for thefluorocarbon ether bisaminophenols with a, ω diiodofluorocarbon ethersas intermediates. U.S. Pat. No. 2,676,985 of Husted, Reilly & Brown inJACS 78:6032 (1956), Grigas and Taurins, Can. J. Chem., vol. 39, 414-419(1961) and Grigas and A. Taurins, Can. J. Chem., vol. 39, 761-764 (1961)describe previously known synthesis routes for formation of amidines.

With respect to ways to speed up slow curing agents, such as BOAP, thereare also traditional accelerators used in the art including organic orinorganic ammonium salts, e.g. perfluorooctanoate, ammoniumperfluoroacetate, ammonium thiocyanate, and ammonium sulfamate; urea;t-butyl carbamate; acetaldehyde ammonia; tetraalkylphosphonium salts,tetraalkylammonium salts, and trialkylsulfonium salts, such asbenzyltriphenylphosphonium chloride, benzyltriphenylphosphonium bromide,benzyltriphenylphosphonium phenolate of bisphenol AF, tetrabutylammoniumhydrogen sulfate, and tetrabutylammonium bromide. However, suchcompounds tend to have side reactions that can result in undesirablebyproducts.

Accordingly, there remains a need in the art for an improved curingagent capable of more easily dispersing in and more quickly curingperfluoroelastomers, particularly cyano curable perfluoroelastomers.There is further a need in the art for a cure accelerator forperfluoroelastomer curatives which accelerate the cure rate of andmaintain the beneficial properties of perfluoroelastomers.

BRIEF SUMMARY OF THE INVENTION

The invention includes monoamidine-based and monoamidoxime-basedcuratives, co-curatives and cure accelerators for perfluoroelastomericcompositions. The invention further includes such materials as curativeshaving the general formula (I):

wherein Y is selected from the group consisting of substituted alkyl,alkoxy, aryl, aralkyl or aralkoxy groups of from 1 to about 22 carbonatoms; substituted or unsubstituted halogenated alkyl, alkoxy, aryl,aralkyl or aralkoxy groups of from about 1 to about 22 carbon atoms, andperfluoroalkyl, perfluoroalkoxy, perfluoroaryl, perfluoroaralkyl orperfluoroaralkoxy groups of from 1 to about 22 carbon atoms; and R¹ ishydrogen; substituted or unsubstituted lower alkyl or alkoxy groups offrom 1 to about 6 carbon atoms; and an amino group; and R² is R¹ orhydroxyl.

The invention also includes bisamidine-based curatives, co-curatives andcure accelerators for perfluoroelastomeric compositions. The inventionfurther includes such compounds as represented by formula (II):

wherein D is selected from the group consisting of unsubstituted orsubstituted halogenated alkyl, alkoxy, aryl, aralkyl or aralkoxy groupshaving from about 1 to about 22 carbon atoms; and perfluoroalkyl,perfluoroalkoxy, perfluoroaryl, perfluoroaralkyl or perfluoroalkoxygroups of from 1 to about 22 carbon atoms; and R¹ and R² are eachindependently selected to be hydrogen; substituted or unsubstitutedlower alkyl or alkoxy groups of from 1 to about 6 carbon atoms and anamino group.

The invention includes a curable perfluoroelastomeric composition,comprising: (a) a perfluoropolymer having at least one curesite monomercomprising a cyano functional group; and (b) at least onemonoamidine-based or monoamidoxime-based curative.

A curable perfluoroelastomeric composition is also within the inventionwhich comprises (a) a perfluoropolymer having at least one curesitemonomer comprising a cyano functional group; (b) a functionalizeddiphenyl-based curative; and (c) a cure accelerator selected from thegroup consisting of at least one monoamidine-based cure accelerator, atleast one monoamidoxime-based cure accelerator, at least onebisamidine-based cure accelerator and combinations thereof. Preferredcurable perfluoroelastomeric compositions are also included in theinvention in which the functionalized diphenyl-based curative hasformula (III):

wherein r is 0 or 1;

-   R³ and R⁴ are each independently selected from the group consisting    of a carbon atom; substituted and unsubstituted and branched and    straight chain carbon groups of from about 2 to about 22 carbon    atoms selected from the group consisting of alkyl groups,    halogenated alkyl groups, and perfluorinated alkyl groups, each of    which groups may be interrupted by at least one oxygen atom;-   each Z is independently selected from the group consisting of an    amino, mercapto, sulfhydryl, or hydroxyl group;-   each J is independently selected to be formula (IV):-   or A; and-   each A is independently selected from the group consisting of    formula (IV); a fluorine atom; and unsubstituted and substituted and    branched and straight chain carbon-based groups which are selected    from group consisting of alkyl, halogenated alkyl, and    perfluoroalkyl groups of from 1 to about 22 carbon atoms; each of    which groups may be interrupted by at least one oxygen atom; wherein    when r is 0 and R³ is a carbon atom, at least one of J and each A is    not formula (IV).

The invention further includes a curative for a perfluoroelastomericcomposition, in which the curative has formula (III) as noted above.

The invention includes a curative for a perfluoroelastomericcomposition, comprising a functionalized diphenyl-based curative whichhas a sufficiently high molecular weight so that the melting point is nogreater than about 240° C., and in certain preferred embodiments is nogreater than about 230° C.

A method for using a compound having formula (I) below is also includedin the invention:

wherein Y is selected from the group consisting of substituted alkyl,alkoxy, aryl, aralkyl or aralkoxy groups of from 1 to about 22 carbonatoms; substituted or unsubstituted halogenated alkyl, alkoxy, aryl,aralkyl or aralkoxy groups of from about 1 to about 22 carbon atoms, andperfluoroalkyl, perfluoroalkoxy, perfluoroaryl, perfluoroaralkyl orperfluoroaralkoxy groups of from 1 to about 22 carbon atoms; and R¹ ishydrogen; substituted or unsubstituted lower alkyl or alkoxy groups offrom 1 to about 6 carbon atoms; and an amino group; and R² is R¹ orhydroxyl, and wherein the compound is used as a curative for aperfluoroelastomeric composition.

A method for curing a perfluoroelastomeric composition is also includedwhich comprises using a mixture of (i) at least one compound selectedfrom the group consisting of monoamidine-based compounds,monoamidoxime-based compounds, and mixtures thereof and (ii) at leastone bisamidine-based compound as co-curatives for theperfluoroelastomeric composition.

A method for accelerating curing of a perfluoroelastomeric compositionis within the invention which method comprises using a cure acceleratorfor a curative, wherein the cure accelerator is selected from the groupconsisting of a monoamidine-based compound, a monoamidoxime-basedcompound, a bisamidine-based compound and combinations thereof.

The invention also includes a method for curing a perfluoroelastomericcomposition comprising using a functionalized diphenyl-based curativehaving a sufficiently high molecular weight such that the melting pointis no greater than about 240° C. as a curative for theperfluoroelastomeric composition, and in certain preferred embodimentsis the melting point is no greater than about 230° C.

Also included within the invention is a method for making a curative.The method comprises (a) reacting an organic alkylacid with an alcoholto form an alkylester; (b) reacting the alkyl ester with ammonia to forman alkylcarboxyamide; (c) reacting the alkylcarboxyamide with adehydrating agent to form an alkyl nitrile; and (d) reacting the alkylnitrile with at least one of ammonia or an amine to form a curative,wherein the curative is capable of curing or accelerating the cure of aperfluoroelastomeric composition.

In addition to the above method, the invention includes a method formaking a bisaminophenol-based curative. That method comprises: (a)reacting an perfluoroacyl fluoride with potassium fluoride to form apotassium alcoholate reaction product; (b) reacting the potassiumalcoholate reaction product with a perfluoroallylfluorosulfate to form aperfluoroallyl ether; (c) reacting the perfluoroallyl ether with anoxidizing agent to form a perfluoroglycidyl ether; (d) reacting theperfluoroglycidyl ether with aluminum chloride in a fluorinated solventto isomerize an epoxide group on the perfluoroglyicdyl ether to aketone; (e) reacting the ketone group with phenol in the presence ofhydrogen fluoride to form a bisphenol-based compound; (f) nitration ofthe bisphenol-based compound to give a bisnitrophenol-based compound;and (g) reduction of the bisnitrophenol-based compound to form abisaminophenol curative, wherein the bisaminophenol-based curative iscapable of curing a perfluoroelastomeric composition.

A substituted bisaminophenyl-based curative for perfluoroelastomershaving cyano-group containing curesite monomers is included within theinvention. The bisaminophenyl-based curative is a substitutedbisaminophenyl-based curative which has formula (IIIa):

wherein R³ is a carbon atom; Z is an amino, sulfhydryl, or hydroxylgroup; J is formula (IV):

and A is selected from the group consisting of unsubstituted andsubstituted and branched and straight chain carbon-based groups, whereinthe carbon-based groups are selected from the group consisting ofperfluoroalkyl and perfluoroalkoxy groups of from 1 to about 22 carbonatoms.

The invention further includes a perfluoroelastomeric compositioncomprising a bisaminophenyl-based curative for perfluoroelastomershaving cyano-group containing curesite monomers, wherein the curative isa substituted bisaminophenyl-based curative which has formula (III):

wherein R³ is a carbon atom; Z is an amino, sulfhydryl, or hydroxylgroup; J is formula (IV):

and A is selected from the group consisting of unsubstituted andsubstituted and branched and straight chain carbon-based groups, whereinthe carbon-based groups are selected from the group consisting ofperfluoroalkyl and perfluoroalkoxy groups of from 1 to about 22 carbonatoms.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to low melting diphenyl-based,preferably diaminophenyl-based and more preferably perfluorinateddiaminophenol-based curatives and co-curatives for perfluoroelastomericcompositions and novel methods of synthesis of preferred functionalizeddiphenyl-based curing agents. The invention is further directed toamidine-based cure accelerators, curatives and co-curatives forperfluoroelastomers. The curing agents and co-curing agents of theinvention show improved mixing with perfluoroelastomeric compositionsand the curatives, co-curatives and accelerators further demonstratefaster cure rates compared with conventional curing agents such as BOAP.Additionally, the amidine-based curatives and accelerators providefaster cures.

As used herein, a perfluoroelastomer may be any cured elastomericmaterial, derived by curing a perfluoroelastomeric composition (asdefined herein) which includes a curable perfluoropolymer having afunctional group to permit cure. A perfluoroelastomer is substantiallycompletely fluorinated with respect to the carbon atoms of theperfluoropolymer. By this it is meant that as would be understood, basedon this disclosure, that some residual hydrogen may exist in thefunctional crosslinking group in some perfluoroelastomeric compositionsaccording to the present disclosure. The perfluoropolymers, used inperfluoroelastomeric compositions to form perfluoroelastomers upon cure,are formed by polymerizing one or more perfluorinated monomers, one ofwhich preferably has a perfluorinated curesite monomer having afunctional group to permit curing.

As used herein, a perfluoroelastomeric composition is a polymericcomposition including a curable perfluoropolymer. The perfluoropolymeras noted above is formed by polymerizing two or more perfluorinatedmonomers, plus at least one perfluorinated monomer which has at leastone functional group to permit curing, i.e. at least oneperfluoropolymeric curesite monomer. Such materials are also referred togeneral as FFKMs (perfluoroelastomers) in accordance with the AmericanSociety for Testing and Materials (ASTM) definition (ASTM-D-1418-01a),incorporated herein fully by reference and are also described furtherherein. The definition provides that a perfluoroelastomer is aperfluorinated rubber of the polymethylene type having all fluoro,perfluoroalkyl, or perfluoroalkoxy substitutent groups on the polymerchain; a small fraction of these groups may contain functionality tofacilitate vulcanization. The perfluoroelastomer composition may includeany suitable curable perfluoropolymer(s) (FFKM) capable of being curedto form a perfluoroelastomer, and one or more curing agents as describedherein.

Such perfluoroelastomeric compositions may preferably include two ormore of various perfluorinated copolymers of at least onefluorine-containing ethylenically unsaturated monomer, such astetrafluoroethylene (TFE); a perfluorinated olefin, such ashexafluoropropylene (HFP); and a perfluoroalkylvinyl ether (PAVE) whichinclude alkyl groups that are straight or branched and which include oneor more ether linkages, such as perfluoro(methyl vinyl ether),perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether) and similarcompounds. Examples of preferred PAVES include those described in U.S.Pat. No. 5,001,278 and in WO 00/08076, incorporated herein by reference.Other suitable PAVEs are described, for example, in U.S. Pat.No.5,696,189 and 4,983,697, also incorporated herein by reference.

Preferred perfluoropolymers are terpolymers or tetrapolymers of TFE,PAVE, and at least one perfluorinated cure site monomer whichincorporates a functional group to permit crosslinking of theterpolymer, at least one of which is a curesite capable of being curedby the curatives and co-curatives of the invention. In one embodiment,the curesite monomer(s) provide curesites which may be cured with eitherthe inventive curative or inventive co-curatives or by other curativesnot within the scope of the invention, but which are capable of havingan accelerated cure when acted on by the cure accelerators of thepresent invention.

Most preferred curesite monomers include those having cyano curesites,regardless of the location of the cyano group, e.g., primary andsecondary cyano group curesite monomers. Examples of cyano curesitemonomers are described in detail herein, and may be found in, forexample, U.S. Pat. No. 4,281,092. Such cyano group containing cure sitemonomers are well known in the art. Combinations of one or more of thesecuresite monomers with each other or with other well known curesitemonomers may also be used within the scope of the invention.

Useful cyano cure site monomers include fluorinated olefins andfluorinated vinyl ethers, each having a cyano group of which thefollowing are general examples:

CF₂═CF—O—[CF₂]_(n)—CN, wherein n is from about 2 to about 12, andpreferably about 2 to about 6;

CF₂═CF—O—[CF₂—CF(CF₃)—O]_(n)—CF₂—CF(CF₃)—CN, wherein n is from 0 toabout 4, preferably from 0 to about 2;

CF₂═CF—[OCF₂CF(CF₃)]_(m)—O—[CF₂]_(n)—CN, wherein m is from about 1 toabout 2, and n is from about 1 to about 4; and

CF₂═CF—O—[CF₂]_(n)—O—CF(CF₃)—CN, wherein n is from 2 to about 4.

Specific examples include primary curesite monomers such asCF₂═CFOCF₂CF(CF₃)OCF2CF2CN (referred to generally as 8-CNVE) andsecondary curesite monomers such as CF₂═CF—O[CF₂]₃—O—CF[CF₃]—CN. Suchcuresite monomers may be used alone or in combination. Especiallypreferred is a combination of curesite monomers as shown below in afluoropolymeric or perfluoropolymeric chain as follows:

wherein p represents a secondary curesite monomer present in afluoropolymer or perfluoropolymers in an amount from about 0.1 to about12 mol %, preferably about 1 to about 4 mol %, and a represents aprimary curesite monomer present in an amount from about 0.1 to about 12mol % and preferably from about 1 to about 7 mol %. It is preferred thatthe molar ratio of the primary curesite monomer to the secondarycuresite monomer in the copolymer is from about 1:1 to about 10:1,preferably 9:1.

It will be understood based on this disclosure that additional types ofcure site monomers which contain cyano groups as curesites and thosewhich do not contain cyano groups may be used in addition to or, incertain cases, in place of the preferred curesite monomers noted above,provided that the curesite monomers are capable of being cured by thepreferred curatives and co-curatives and/or capable of experiencing anaccelerated curing reaction when using the cure accelerators of theinvention as described herein. Common examples of other types ofcuresite monomers include olefins, including partially or fullyhalogenated olefins, such as ethylene, vinylidene fluoride, vinylfluoride, trifluoroethylene, bromotetrafluorobutene,bromotrifluoroethylene, 1-hydropentafluoropropene and2-hydropentafluoropropene. Such additional cure site monomer(s) may bepresent in ranges as noted above and are preferably are generallypresent in amounts of about 0.1 to about 5 mole percent, more preferablyabout 0.1 to about 2.5 mole percent, and most preferably about 0.3 toabout 1.5 mole percent.

Other additives, such as co-curatives, curing agents or accelerators,other than those of the present invention; processing aids; fillers andthe like may also be included as optional components of theperfluoroelastomeric compositions of the invention. Such additivesinclude fillers such as graphite, carbon black, clay, silicon dioxide,fluoropolymeric particulates (for example, TFE homopolymer and copolymermicropowders), barium sulfate, silica, titanium dioxide, acid acceptors,cure accelerators, glass fibers, or polyaramid fibers such as Kevlar,other curing agents and/or plasticizers or other additives known or tobe developed in the fluoroelastomeric art and perfluoroelastomeric art.Preferred perfluoropolymers/perfluoroelastomers include Simriz®,available from Freudenberg of Germany, Dyneon®, available from MinnesotaMining & Manufacturing in Minnesota, Daiel-Perfluor®, available fromDaikin Industries, Ltd. of Osaka, Japan. Similar materials are alsoavailable from Ausimont S.p.A. in Italy and from Federal State UnitaryEnterprise S.V. Lebedev Institute of Synthetic Rubber in Russia.

Preferred curatives and co-curatives for use in the fluoroelastomeric orperfluoroelastomeric compositions of the present invention are thosewhich include functionalized diphenyl compounds which include branchedor straight chain alkyl, halogenated alkyl, perhalogenated alkyl, andpreferably perfluoroalkyl type compounds that may or may not have one ormore oxygen atoms and which may or may not be substituted, and whichhave at least two aminophenyl groups, preferably two aminophenol groups,but which have a sufficiently high molecular weight (extended chains) sothat the melting point is preferably no greater than about 240° C., morepreferably no greater than about 230° C., and most preferably to about225° C. to thereby enhance compatibility and provide fast curingreactions of perfluoroelastomeric compositions, particularly thepreferred perfluoroelastomers having cyano-type curesite monomers.

Such curing agents are preferably diphenyl-based curatives of formula(III):

In formula (III), r may be 0 or 1. In formula (III), further R³ and R⁴are independently selected to be a carbon atom or branched or straightchain carbon-based groups (which may be further substituted orunsubstituted) of from about 2 to about 22 carbon atoms in any of suchchains (whether straight or branched), more preferably such chains arefrom 10 to 22 carbon atoms, and which groups are selected from thefollowing exemplary groups: alkyl groups, fully or partially halogenatedalkyl groups, and preferably perfluorinated alkyl groups, each of whichgroups may be interrupted by at least one oxygen atom, and in whichbranching chains may include such groups as, for example, haloalkyl,fluoroalkyl and trifluoroalkyl. Substitutions acceptable for use informula (III) and other formulae described herein as containingsubstitutable groups, including the preferred formulations in accordancewith formula (III) described below, may be the same as noted herein forformulas (I) and (II) to the extent such substitutions may be desiredfor a given curing reaction. Z is preferably an amino, mercapto,thiphenol, sulfhydryl or hydroxyl group, with the hydroxyl group beingmost preferred.

Each J is independently selected to be formula (IV):

or the same as A, and A may be independently selected on either side ofR³ in formula (III) to be formula (IV), a hydrogen atom, a fluorineatom, or a branched or straight chain (substituted or unsubstituted)carbon-based group which is selected from the following groups: analkyl, a partially or fully halogenated alkyl, or perfluoroalkyl groups,more preferably a perfluoroalkyl group, of from one to about 22 carbonatoms; each of which groups may be interrupted by at least one oxygenatom, and in which branching chains may include such groups as, forexample, haloalkyl, fluoroalkyl and trifluoroalkyl. When r is 0 and R³is a carbon atom, at least one of J and each A is not formula (IV).While it is within the scope of the invention for an A group to beformula (IV), it is preferred that only two such groups appear incuratives of formula (III), such that if r is 0 and J is formula (IV)above, it is preferred that neither A group is formula (IV).

Preferred structures when r=0 in formula (III) and J meets formula IVabove, include structures where R³ is a carbon atom and those in whichR³ is a straight or branched alkyl or perfluorinated alkyl group whichmay or may not contain oxygen. Further preferred are structures in whichwhen r is 0, R³ is a carbon atom, J is formula (IV), one A istrifluoromethyl and the other A is selected from the group consisting oflinear and branched chain perfluoroalkyl and perfluoroalkylether groupsof from 2 to 22 carbon atoms.

Preferred structures where r is 0, J meets formula IV and R³ is a carbonatom include the following structures (V) through (VII) in which qpreferably ranges from 0 to 6, however q being greater than 6 is alsowithin the scope of the invention.

Further preferred examples of formula III when r is 0, R³ is a carbonatom, A is CF₃ on one side of R³ and A is a chain of varied length onthe other side of R³ include the following materials as set forth inTable 1 below in accordance with the structure of the chain representedby the A group opposite the A which is CF₃. As can be seen from Table 1,the preferred compounds are similar in color and appearance but differin melting point, providing a wider range of options for curatives interms of compatibility and curing speed in fluoroelastomeric andperfluoroelastomeric compositions. TABLE 1 Melting Point A ColorAppearance (° C.) CF₃OCF₂CF₂OCF₂ White to creamy powder 210CF₃OCF₂CF₂CF₂OCF₂ White to creamy powder 175 CF₃O(CF₂O)₂CF₂CF₂OCF₂ Whiteto creamy powder 142 CF₃O(CF₂O)₃CF₂CF₂OCF₂ White to creamy powder 100CF₃O(CF₂O)₄CF₂CF₂OCF₂ White to creamy powder  75 CF₃OCF₂ White to creamypowder 235 CF₃OCF₂OCF₂ White to Creamy powder 190 CF₃O(CF₂O)₂CF₂ Whiteto Creamy powder 155 CF₃O(CF₂O)₃CF₂ White to Creamy powder 120CF₃OCF₂CF₂CF₂OCF₂ White to Creamy powder 220

Preferred exemplary structures when r is 0 in formula (III), J is as informula IV above and R³ is a straight or branched chain group such asalkyl, halogenated alkyl, and preferably a perfluorinated alkyl group,which may or may not contain oxygen, include structures such as (VIII)and (IX) below in which the biaminophenyl groups are not in the bisposition as are the structures shown above, but are in terminalpositions separated by a chain providing a molecular weight which issufficient to provide a melting point of no greater than about 240° C.,more preferably no greater than about 230° C., and most preferably nogreater than about 225° C. In such structures, A may be as describedabove. While it is within the scope of the invention for an A group tobe formula (IV), it is preferred that when J is formula (IV), only twosuch groups appear in curatives of formula (III) and that it ispreferred in such structures that neither A is formula (IV):

wherein x, y and z are each independently selected to be from 0 to about20, preferably from 0 to 10, wherein preferably x+y+z total no more thanabout 20, and preferably from about 9 to about 20 and L is hydrogen,halogen such as fluorine, chlorine, bromine and iodine, alkyl,halogenated alkyl and preferably perfluorinated alkyls such astrifluoromethyl, most preferably L is fluorine or trifluoromethyl. Afurther example includes:

wherein L, x, z are as defined above, but x and z are each independentlypreferably from 0 to about 10, and wherein x+y totals preferably no morethan about 20, preferably from about 9 to about 20. It should beunderstood that structures in accordance with Formula (III) where r is 0and R³ is straight or branched alkyl or perfluorinated alkyl group whichmay or may not contain oxygen, include variations of formulae VIII andIX wherein fluorine atoms may be substituted and/or L may be branchedinto longer structures as shown below, for example in formulae X-XII:

wherein s is preferably 1 to about 6, and x, s and z are as previouslydefined, with x+s+z preferably totaling no more than about 20, and morepreferably at a minimum, s is 1 and x and z are 0.

When r is not 0 in formula (III), structures are included within thescope of the 10 invention which have at least two aminophenyl groups,but wherein the aminophenyl groups are not in the bis position and/ornecessarily in a terminal position. In such structures, at least oneaminophenyl group is located on R³ and R⁴ at any location along each oftheir chains, with J and A being as defined above, but in preferredembodiments, only two such aminophenyl groups are present in thecompound as a whole such that when two such groups are already arepresent it is preferred that J and A are not formula (IV), even thoughsuch compounds are clearly contemplated as being within the scope of theinvention. Exemplary such bisaminophenol structures are as follows,however it should be understand that variations of such structures arealso included within the invention in accordance with formula (III):

For example, in formula XIII above, both A groups are CF₃, R³ is

R⁴ is

the J group on R³ is F and the J group on R⁴ is L, and x and z are asdescribed below. Further examples include:

wherein L, x and z are as described above, however, in formula XIII,XIV, XV and XVI, it is preferred that and that x and z total no morethan 19. It is also preferred that in all of the formula noted above, Lis fluoro, perfluoroalkyl or perfluoroalkoxy.

Other preferred formula include formula (III), wherein when r is 1, eachA and each J are fluorine, R³ is a carbon atom and R⁴ is selected fromthe group consisting of linear and branched chain perfluoroalkylene andperfluoroalkylether groups of from 2 to 22 carbon atoms, wherein one Aand one J are both bonded to the terminal carbon atom of R⁴ .

Various synthetic routes exist and/or may be developed for making thevarious preferred curing agents according to formula (III). The curingagents are within the scope of the invention regardless of whichchemical route is used to obtain them. Existing routes are described formaking some of the compounds according to formula III as described in R.C. Evers, J. Polym. Sci. 16, 2833-2848 (1978), incorporated herein byreference. Further, the present invention includes several novel routesfor preparing preferred compounds in accordance with formula (III). Oneroute involves using epoxide-ketone reactions as described further belowand another involves an organomagnesium route also described furtherherein. However, while novel methods are presented herein, it should beunderstood that any synthesis method may be used to make the novelcuratives and co-curatives of the invention and that the invention ofproviding functionalized diphenyl-based curatives and co-curatives whichhave molecular weights sufficiently high to provide a melting point ofno greater than about 240° C., more preferably no greater than about230° C., or most preferably no greater than about 225° C. areencompassed within the invention including those having formula (III)regardless of their methods of synthesis.

Preferred reactions include reacting a perfluoroalkylacid halide,preferably a perfluoroalkyl acid fluoride, i.e., an acyl-group compound,preferably a perfluoroacyl fluoride with potassium fluoride to form analcoholate of the initial compound. The potassium alcoholate reactionproduct, is then reacted with perfluoroallyl fluorosulfate to form theperfluoroallylether of that material.

This perfluoroallyl ether reactant product is then further reacted withan oxidizing agent, i.e., oxidized, wherein the oxidizing agent ispreferably oxygen but is not limited thereto, to form aperfluoroglycidyl ether. The perfluoroglycidyl ether, which is thenreacted with aluminum chloride in a fluorinated solvent, isomerizes theepoxide group on the perfluoroglycidyl ether to a ketone. The ketonecompound is then reacted with a phenyl having functional group Z(preferably where Z is OH and the phenyl is phenol) in the presence ofhydrogen fluoride to form a bisphenyl-based compound, preferably abisphenol compound.

Such a bisphenyl- or bisphenol-based compound is then nitrated withnitric acid (or a similar useful nitrating compound) to provide an NO₂group on each phenyl group and form a bisnitrophenyl-based orbisnitrophenol-based compound. This compound is then reduced using asuitable reducing agent to form the desired compound havingbisaminophenyl, preferably bisaminophenol groups each having the Zradical (preferably bisaminophenol groups) of Formula IV which iscapable of curing a perfluoroelastomeric composition.

Such an exemplary synthesis route for forming novel curatives andco-curatives according the invention may be illustrated with referenceto structures such formulae V and VI and similar compounds where one Ain formula III is CF₃, R³ is a carbon atom, J is formula IV and r is 0,includes the following basic reaction scheme wherein R′ refers to aportion of the chain that is part of the A group (CF₂—O—CF₂—R′)extending opposite the A which is CF₃:

A further exemplary reaction scheme for forming compounds according toformula (III) when R³ is a carbon atom, r is 0, J is formula (IV), one Agroup is CF₃ and the other A group (referred to in the mechanism belowas A′) is CF₃O(CF₂O)_(q)CF₂— such as compounds in formula (VII) andsimilar compounds includes a method using organomagnesium compounds. Inthis synthesis route, an alkylmagnesium halide, halogenated alkylmagnesium halide or a perfluoroalkyl magnesium halide, and preferably aperfluoromagnesium iodide such as trifluoromethylmagnesium iodide isreacted with an alkyl, halogenated alkyl or perfluorinated acyl halide(such as an A chain in formula (III)) wherein the acyl halide includes ahalogenated ketone group. The resulting compound releases magnesiumhalide to leave a ketone group on the acyl halide. This ketone is thenfurther reacted with a substituted phenyl compound having a Z functionalgroup (preferably hydroxyl) to form a bisphenyl functional group(preferably bisphenol) at the ketone site, which is then nitrated andsubsequently reduced in the manner noted above. A sample of suchmechanism is as shown below:

Alternatively, each of the two phenyl groups may be provided to R³ or R⁴at different locations and/or terminal locations by using known chemicalsubstitution techniques and routes to achieve various other formulae inaccordance with formula (III). One such substitution route is shown inEvers, noted above herein, which obtains fluorocarbon bisaminophenols(some of which are represented by formula (III)) by reactingdiiodoperfluoroalkane intermediates with iodophenyl acetate, hydrolyzingthe product to obtain a bisphenol, nitrating and then reducing thedinitrobisphenol to obtain a bisaminophenol.

It also possible to employ other curing agents or more than one curingagent depending on the cure site monomers present, such as an organicperoxide, an organometallic compound such as an organotin, diamines,amidines, conventional bisaminophenols and/or bisaminothiophenols, etc.or mixtures thereof. In addition, perfluoropolymers may be cured usingradiation curing technology as an assist or to cure other curesites notcured by the curatives and co-curatives of the invention.

The amount and type of curative or co-curing agent according to theinvention which should be used should be chosen to optimize the desiredproperties of the cured fluoroelastomer or perfluoroelastomer (includingits resistance to chemical attack, specific elongation-at-break,resistance to compression set, flexural modulus, tear strength, hardnessand the like). The amount used will depend on the degree of crosslinkingdesired, the type and number of cure sites to be cured by the inventivecuratives, the number of other cure sites to be cured by other curativesnot within the scope of the invention, and the cure rate desired. Apreferred amount of curative is an amount as much as equivalent to anamount in slight excess of the amount required to react with thosecuresites present in the fluoroelastomeric or perfluoroelastomericcomposition which are capable of reacting with the curatives andco-curatives of the invention. Preferably, about 0.1 to about 10 partsby weight of the curing agent per about 100 parts of fluoropolymer orperfluoropolymer is used, more preferably about 1 to about 4 parts byweight. When used as a co-curative, the amount is preferably less, sinceother cure reactions are occurring, however, that too depends on thenumber of sites and other parameters noted above.

The invention includes amidine-based or amidoxime-based curatives whichmay function as curatives or co-curatives, and also as cureaccelerators, and may be employed either alone or with thebiphenyl-based curatives and co-curatives of the invention as describedherein or with other curatives not within the invention, or used tofurther accelerate the rate of cure of the biphenyl-based curatives andco-curatives of the invention nor other curatives outside of theinvention within perfluoroelastomeric compositions.

Suitable amidine and amidoxime curatives and accelerators includemonoamidines, monoamidoximes and bisamidines as described herein. Othercure accelerators known in the art such as organic or inorganicammoniums salts, e.g. perfluoroctonaoate, ammonium perfluoroacetate,ammonium thiocyanate, and ammonium sulfamate; urea; t-butyl carbamate;acetaldehyde ammonia; tetraalkylphosphonium salts, tetraalkylammoniumsalts, and trialkylsulfonium salts, such as benzyltriphenylphosphoniumchloride, benzyltriphenylphosphon ium bromide,benzyltriphenyl-phosphonium phenol ate of bisphenol AF,tetrabutylammonium hydrogen sulfate, and tetrabutylammonium bromide mayalso be used in conjunction with the novel biphenyl-based curatives andco-curatives of the invention if desired. However, of accelerators aredesired for the novel biphenyl-based curatives and co-curatives of theinvention, it is preferred that the amidine- and amidoxime-based cureaccelerators described herein be used to accelerate the cure of thebiphenyl-based curatives and co-curatives of the invention.

The preferred accelerators for the biphenyl-based curatives andco-curatives of the present invention are amidine-based andamidoxime-based cure accelerators, which also may themselves function asindependent curatives or co-curatives in perfluoroelastomericcompositions. These amidine-based and amidoxime-based materials includemonoamidines and monoamidoximes of the following formula (I) andbisamidines of formula (II) described further below. The monoamidinesand monoamidoximes may be represented by formula (I)

wherein Y may be a substituted alkyl, alkoxy, aryl, aralkyl or aralkoxygroup or an unsubstituted or substituted fully or partially halogenatedalkyl, alkoxy, aryl, aralkyl or aralkoxy group having from about 1 toabout 22 carbon atoms. Y may also be, and preferably is, aperfluoroalkyl, perfluoroalkoxy, perfluoroaryl, perfluoroaralkyl orperfluoroaralkoxy group of from 1 to about 22 carbon atoms and morepreferably a perfluoroalkyl or perfluoroalkoxy group of from about 1 toabout 12 carbon atoms, and more preferably from 1 to 9 carbon atoms; andR¹ may be hydrogen or substituted or unsubstituted lower alkyl or alkoxygroups of from one to about 6 carbon atoms, or an amino group. R² may beindependently any of the groups listed above for R¹ or hydroxyl.Substituted groups for Y, R¹ or R² include, without limitation,halogenated alkyl, perhalogenated alkyl, halogenated alkoxy,perhalogenated alkoxy, thio, amine, imine, amide, imide, halogen,carboxyl, sulfonyl, hydroxyl, and the like. Preferred embodimentsinclude those in which R² is hydroxyl, hydrogen or substituted orunsubstituted alkyl or alkoxy groups of from 1 to 6 carbon atoms, morepreferably hydroxyl or hydrogen. Also preferred are embodiments in whichR¹ is hydrogen, amino or a substituted or unsubstituted lower alkyl offrom 1 to 6 carbon atoms while R² is hydrogen or hydroxyl. Mostpreferred are embodiments where R¹ is hydrogen. Further preferredembodiments include those in which Y is perfluoroalkyl, perfluoroalkoxy,substituted or unsubstituted aryl groups and substituted orunsubstituted halogenated aryl groups having the chain lengths as notedabove.

Exemplary monoamidine-based and monoamidoxime-based curatives accordingto formula (I) include perfluoroalkylamidines, arylamidines,perfluoroalkylamidoximes, arylamidoximes and perfluoroalkylamidrazones.Specific examples include perfluorooctanamidine,heptafluorobutyrylamidine, benzamidine, trifluoromethylbenzamidoxime,and trifluoromethoxylbenzamidoxime. Curatives as noted according toformula (I) may be used alone or in combinations, such as combinationsof the foregoing exemplary compounds.

The curatives according to formula (I) are preferably capable of curingperfluoroelastomeric compositions, particularly those with at least onecyano curesite monomer. The curatives according to formula (I) of thepresent invention are also monoamidine-based and monoamidoxime-basedcure accelerators which are capable of accelerating the cure ofperfluoroelastomeric compositions comprising at least one cyano curesitemonomer, and more preferably compositions which also includediphenyl-based curatives (including the novel diphenyl-based curativesof the invention), such as bisaminophenol and its derivatives. Suitableexamples of monoamidines include benzamidines and perfluoroalkylamidines. Particularly suitable examples are perfluorooctanamidine andperfluoroheptanamidine.

The invention also includes bisamidine-based curative and cureaccelerators for fluoroelastomeric and perfluoroelastomeric compositionsrepresented by formula (II):

wherein D may be unsubstituted or substituted fully or partiallyhalogenated alkyl, alkoxy, aryl, aralkyl or aralkoxy groups having fromabout 1 to about 22 carbon atoms, or more preferably perfluoroalkyl,perfluoroalkoxy, perfluoroaryl, perfluoroaralkyl, or perfluoroaralkoxygroups of from 1 to about 22 carbon atoms and more preferably aperfluoroalkyl or perfluoroalkoxy group of from about 1 to about 12carbon atoms. R¹ and R² are as defined above with respect to formula(I), however, in formula (II), R² is not hydroxyl, it is independentlyselected to be the same as R¹ noted above. Further, D, R¹ and R² mayeach be substituted by one of more of the groups noted above withrespect to formula (I). Most preferably herein in formula (II), both R¹and R² are hydrogen.

Oxygen atoms are preferably included in the form of ether linkages in Y,R¹ and R². While it is preferred that Y is straight or branched, it isalso within the scope of the invention that Y could be a cyclic oraromatic structure, which is capable of being substituted as notedabove.

With respect to the bisamidines of formula (II), it is preferable that Dis a fluorinated, more preferably perfluorinated. If D is only partiallyhalogenated, however, it is preferred that the carbon atoms adjacent theamidine groups each have two hydrogen substituents to stabilize thecompound. Oxygen atoms in D are preferably also in the form of etherlinkages. While it is preferred that D is straight or branched chain, itis also within the scope of the invention that D is a cyclic or aromaticstructure, which may be further substituted. Particularly suitableexamples of such bisamidines include perfluorosuberamidine andperfluorosebacamidine. Suitable perfluoroalkyl monoamidines andbisamidines can be purchased from SynQuest Laboratories, Inc. ofAlachua, Florida. Such materials are commercially available from FederalState Unitary Enterprise S.V. Lebedev Institute of Synthetic Rubber inRussia.

The bisamidines of the invention can be used as cure acceleratorscapable of accelerating the cure of perfluoroelastomers, particularlywhen the perfluoroelastomeric composition includes at least one cyanocuresite monomer. Preferred exemplary bisamidines according to theinvention include perfluorosuberamidine and perfluorosebacamidine.

It is understood that when the above amidine, amidoxime materials areused as accelerators, the amount is chosen may be based upon theparticular perfluoroelastomer chosen, the curatives and/or co-curativeschosen and the desired cure properties, such as the time necessary todevelop a minimum specified Mooney viscosity, the ability of thecomposition to resist deformation, and a maximum specified torquemeasured by a moving die rheometer. Suitable amounts include about 0.1to about 5 parts of accelerator per about 100 parts of perfluoropolymer.

In preparing monoamidines, monoamidoximes and bisamidines, the inventionis not restricted with respect to any particular synthesis method formaking these compounds. Any chemical synthesis and/or use ofcommercially available monoamidines, monoamidoximes and bisamidines areacceptable. However, the present invention does include a novelsynthesis method as described herein. With respect to preparingmonoamidines useful within the invention, an alkyl acid (i.e., anorganic acid such as a carboxylic acid containing compound), halogenatedalkyl acid and preferably a perfluorinated alkyl acid is first convertedto a nitrile form by combining the alkyl acid (or similar compound asnoted) with an alcohol, such as an alkanol, e.g. methanol or ethanol inthe presence of an inorganic acid such as sulfuric acid. The mixture isboiled, washed with water and dried, preferably using an suitablematerial such as MgSO₄. The resulting product is an alkylester,halogenated alkyl ester or perfluoroalkyl ester which is then reactedwith a nitrogen containing reactant such as ammonia, preferably ammoniagas. A reaction is allowed to proceed with control of the reactiontemperature to produce a carboxyamide structure, such as analkylcarboxyamide. This reaction product is then combined with adehydrating agent, such as, for example, phosphorus pentaoxide, mixedand refluxed under heat and the product is converted to an alkylnitrile, such as cyano-functional alkyls including an alkylcyano,halogenated cyano or perfluoroalkyl cyano compounds. The alkyl nitrilecompound is then added to a reaction chamber filled with at least onenitrogen containing compound, such as preferably an amine compound orammonia in liquid or gas form, preferably in liquid form. It ispreferred that the nitrogen-containing compound such as ammonia ispresent in excess, preferably about 10 fold excess, with respect to theadded alkyl nitrile (preferably cyano-functional) compound. Afteraddition of the alkyl nitrile compound to the chamber including thenitrogen containing compound, the temperature is raised, preferablyslowly, to about ambient temperature and excess nitrogen containingcompound (such as ammonia) is removed. Solid white product is typicallythe resulting compound which is an alkyl, halogenated alkyl orperfluorinated alkyl group having a monoamidine structure. While theforegoing represents a preferred synthesis route for making monoamidinesaccording to the invention, any method known or to be developed may beemployed in making the bisamidines, monoamidines or monoamidoximes ofthe invention without departing from the scope of the invention. Theresulting monoamidines and monoamidoximes of the invention are useful ascuratives and are capable of curing or accelerating the cure ofperfluoroelastomeric compositions as noted above. Preferred compoundsmade according to the above method include perfluoroheptanamidine.

The perfluoroelastomeric composition is mixed or blended with any of theabove additives by any conventional means or apparatus, including withtwo-roll mills and internal mixers. For example, the composition may beblended using an internal mixer such as those commercially availablefrom Banbury, C.W. Bradender Instruments, Inc. of Hackensack, N.J. andfrom Morijama of Farmingdale, N.Y. Preferably, the curative(s) andco-curative(s) of the invention and/or the cure accelerators of theinvention are added once all of the other ingredients desired areblended, however, it should be understood that the order in which suchmaterials are provided is not limiting the scope of the invention. Thecurable compositions may then be processed and cured/crosslinked byapplication of heat and/or pressure to form an elastomeric part, such asa seal. After curing, postcuring may be desirable to enhance physicalproperties and is also within the scope of the invention.

Additional specific examples of preferred monoamidine cure accelerators,which may also be used as direct curative(s) or co-curative(s) are asfound in Table 2, wherein R¹ and R² are both hydrogen and the compoundsare categorized by the composition of Y in formula (I) above. TABLE 2 UVSpectrum Y Color Appearance Melting Point ° C. (nm) —CF₃ White to liquidTboiling = 40-44 212 creamy (14 mm Hg) —C₂F₅ White to powder 50 212creamy —C₃F₇ White to powder 52 212 creamy —C₄F₉ White to powder 58 212creamy —C₅F₁₁ White to powder 66 212 creamy —C₆F₁₃ White to powder 75212 creamy —C₇F₁₅ White to powder 87 212 creamy —C₈F₁₇ White to powder98 212 creamy —C₉F₁₉ White to powder 116  212 creamy

The invention will now be described by reference to the followingnon-limiting examples:

EXAMPLE 1

A bisaminophenol derivative according to formula (III)(2,2-bis[3-amino-4-hydroxyphenyl]4,7,9,11tetraoxa-1,1,1,3,3,5,5,6,6,8,8,10,10,12,12,12-hexadecafluorododecane)was prepared in which R³ is a carbon atom, r is 0, J is a structure asin formula (IV), one A is —CF₃ and the other A is—CF₂OCF₂CF₂(OCF₂)₂OCF₃. Such structure is shown above in representativeform in formula (V). In preparing such compound, a perfluorinatedpolyether ketone was first formed in accordance with an epoxide-ketoneroute as described herein. A flask protected by a continuous flow of drynitrogen gas was charged with potassium fluoride in an amount of 11.6 g(0.2 mole) and 100 ml Diglyme that had already been dried bydistillation from CaH₂. The mixture was stirred for 15 minutes. To thismixture was added at room temperature with good stirring 60 g (0.19mole) of 3,5,7-trioxa-2,2,4,4,6,6,8,8,8-nonafluorooctanoyl fluoride wereadded for 1 to 1.5 hours, at room temperature and with adequatestirring. After addition was completed, the mixture was stirred anadditional 2 hours until all the potassium fluoride was dissolvedforming the potassium alcoholate salt, CF₃O(CF₂O)₂CF₂CF₂OK. The presenceof the alcoholate and completion of the reaction was confirmed by thedisappearance of the acid fluoride band at 1890 cm⁻¹ in the infraredspectrum.The line 1890 cm⁻¹ corresponds to:

The reaction described above is characterized by the following:

Following formation of the alcoholate above, the flask containing theabove potassium alcoholate solution was cooled to 10° C. and a droppingfunnel was attached. Perfluoroallylfluorosulfate in an amount of 48 g(0.21 mol) was then added slowly (dropwise) through a dropping funnelwith a temperature of 10 to 15° C. being maintained. After an additionaltwo hours stirring, two liquid layers formed. the layers were separatedand the upper layer was distilled at a temperature of 60° C. under avacuum of 0.5 mm Hg. The distillate was combined with the bottom layer.The crude product was washed with water to remove the KOSO₂F salt,separated and the upper aqueous layer discarded. The lower layer wasdried by distillation from P₂O₅ to obtain crude perfluoroallyl ether(4,7,9,11-tetraoxa-1,1,2,3,3,5,5,8,8,10,10,12,12,12-hexadecafluorododecene)in 95% yield. The crude perfluoroallyl ether was fractionally distilledand a fraction boiling at 88° C. was collected and identified by F¹⁹NMR, IR spectroscopy (absorption band at 1795 cm⁻¹ corresponding to—CF═CF₂) and elemental analysis. The elemental analysis is as follows:

calculated for C₈F₁₆O₄: C, 20.68%; F, 65.51%. experimentally found: C,20.24%; F, 65.63%.The reaction described above is shown representatively below:

The above perfluoroallyl ether was oxidized in a well-agitated 1-literstainless steel reactor. The reaction was carried out for 12 hours at atemperature of 80 to 120° C. and an oxygen pressure of 12 to 20 atmgauge (150 to 300 psig). The reaction mixture was distilled at 90° C.and a pressure of 100 mm Hg to yield the perfluoroglycidylether(4,7,9,11-tetraoxa-1,1,2,3,3,5,5,6,6,8,8,10,10,12,12,12-hexadecafluorododecane-1,2-oxirane)in 85% yield. The structure was confirmed by F¹⁹ NMR, the presence of anIR band at 1530 cm⁻¹ (epoxide) corresponding to epoxide

and the absence of an IR band at 1795 cm ⁻¹ (absence of —CF═CF₂—). Thereaction noted above is shown representatively below:

A flask was charged with three (3) g of AlCl₃ and 10 ml Freon 113 andthe mixture was stirred at room temperature for 40 minutes. Most of theFreon 113 was removed at reduced pressure leaving a pasty residual. Tothis was added dropwise with stirring 30 g of the aboveperfluoroglycidyl ether over a period of 10 to 15 minutes. The mixturewas then stirred at 50° C. for 2 hours. The course of the isomerizationwas monitored by infrared spectroscopy. The epoxide band at 1530 cm⁻¹was replaced by the ketone band at 1796 cm⁻¹. Crude perfluoroketone wasisolated in 90% yield by distillation at 60° C. and 100 mm Hg. The pureperfluoroketone(4,7,9,11-tetraoxa-1,1,1,3,3,5,5,6,6,8,8,10,10,12,12,12-hexadecafluorododecan-2-one)was obtained by fractional distillation at b.p. of 114° C. Its identitywas confirmed by F¹⁹ NMR and its purity by gas-liquid chromatography.The final reaction to form the perfluoroketone is shown representativelybelow:

A metal ampoule was charged with 94 g of phenol, 240 g ofperfluoroketone and 100 g of hydrogen fluoride, sealed and heated for 10hours at a temperature of 95° C. The hydrogen fluoride was removed bydistillation and the solid bis-phenol was purified by recrystallizationfrom toluene and chloroform. The yield was pure bisphenol(2,2-bis[4-hydroxyphenyl]4,7,9,11-tetraoxa-1,1,1,3,3,5,5,6,6,8,8,10,10,12,12,12-hexadecafluorododecane)at 89%. The structure was confirmed by F¹⁹ NMR.

A four-neck flask was fitted with an agitator, reflux condenser,dropping funnel and thermometer. A solution of 39.2 g of the abovebisphenol product and 0.1 g NaNO₂ in 130 ml glacial acetic acid wasprepared in the flask. With the solution maintained at 40-45° C., asolution of nitric acid and 20 ml glacial acetic acid was added. Whenthe addition was completed the reaction mixture was heated for 2 hoursat a temperature of 60° C., then for 3 hours at a temperature of 80° C.Water was added and the yellow-red oil that resulted was separated,dissolved in toluene and dried over MgSO₄. Toluene solvent was distilledoff at 200-300 mm Hg pressure using a water-jet pump. The residualbisaminophenol product(2,2-bis[3-nitro-4-hydroxyphenyl]4,7,9,11-tetraoxa-1,1,1,3,3,5,5,6,6,8,8,10,10,12,12,12-hexadecafluorododecane)was obtained in an amount of 54.7 g for a 81.1% yield.

A four-neck flask was fitted with an agitator, reflux condenser,dropping funnel and thermometer. A solution of the bisaminophenol abovein 100 ml ethanol was prepared in the flask and 1.5 g catalyst was added(5% Pt on carbon). With agitation, 12 g of 100% hydrogen peroxide wasadded and the mixture was refluxed for 4 hours. The mixture was cooledfiltered to remove the catalyst and diluted with three volumes of water.The aqueous mixture was acidified with acetic acid to a pH below 6. Theprecipitated product was collected by filtration, air-dried andrecrystallized from ethyl acetate. Pure bisaminophenol(2,2-bis[3-amino-4-hydroxyphenyl]4,7,9,11-tetraoxa-1,1,1,3,3,5,5,6,6,8,8,10,10,12,12,12-hexadecafluorododecane)product melting at 142° C. was obtained in 91.0% yield (45.7 g). Thestructure was confirmed by F¹⁹ NMR.

EXAMPLE 2

In making the same bisaminophenol derivative product as in Example 1, analternate route was taken to prepare the perfluoroketone usingorganomagnesium synthesis which involves condensation of trifluoromethylmagnesium iodide with a perfluoroalkanoyl halide. The synthesis isdescribed in J.Am.Chem.Soc., pp. 1273-77 (1954):

A flask containing 28.8 g Mg and a few crystals of iodine was heatedwith stirring to 60° C. until the iodine color disappeared. The flaskwas cooled to room temperature and 300 ml of diethyl ether were added.The flask cooled to −40° C. and 19.0 g of CF₃I were slowly addeddropwise over a period of 3 hours to produce a solution containing 8.8 g(40% yield) of CF₃MgI. The temperature was raised to 30° C., and3,5,7-trioxa-2,2,4,4,6,6,8,8,8-nonafluorooctanoyl chloride) was addedover a period of one hour while stirring. After an additional 7 hoursstirring at room temperature the perfluoroketone product,4,6,8-trioxa-1,1,1,3,3,5,5,7,7,9,9,9-dodecafluorononan-2one, wasisolated by distillation at reduced pressure (b.p. of 1° C. at 15 mmHg). The structure was confirmed using F¹⁹ NMR. This perfluoroketone canbe converted via the procedures described in Example 1 to form abisaminophenol(2,2-bis[3-amino-4-hydroxyphenyl]4,6,8-tetraoxa-1,1,1,3,3,5,5,7,7,9,9,9-dodecafluorononane)with melting point 115° C.

EXAMPLE 3

Monoamidines were synthesized in accordance with the method of theinvention as follows. In a four-neck flask, provided with a mixer,thermometer, back-flow condenser and a dropping funnel, 41.1 g (0.01mole) of dry C₇F₁₅COOH were added and blended with 32.0 g methanol and19. ml of concentrated H₂SO₄. The mixture was boiled for 6 hours, thenwashed with water and dried with MgSO₄. The product, an ester, wasdistilled (T_(boiling) of 158° C.). The yield was 90-95% (39.2 g) usingthe procedure as described in U.S. Pat. No. 2,570,116 (1951). In afour-neck flask, provided with mixer, thermometer, condenser and thetube for introduction of gas, 39.2 g of C₇F₁₅COOCH₃ and 100 ml diethylether were added. Additionally, ammonia gas was provided, and ice wasused as necessary to cool the flask. The completion of the reaction waschecked by gas-liquid chromatography by noting the absence ofC₇F₁₅COOCH₃ in the ether solution. The ether was distilled off, and thesolid product was dried in air. 37.0 g of C₇F₁₅CONH₂ were obtained (ayield of 97.9%) and the product had a T_(boiling) of 90° C. In around-bottom flask, 37.0 g of C₇F₁₅CONH₂ (0.0896 mol) that had beenground into a fine powder and 63.6 g of P₂O₅ were added. The materialswere thoroughly mixed, and a reflux condenser was placed on the flaskand heated at 100-200° C. The product C₇F₁₅—CN was obtained in an amountof 30.1 g (a yield of 85%), and had a T_(boiling) of 90° C. The reactionscheme as noted above appears representatively below:

Such cyano terminal compound was then converted to monoamidine formhaving a formula C₇F₁₅CN using a technique such as that used in Example4 below.

EXAMPLE 4

A ten-fold excess, fifty (50) ml, of anhydrous ammonia gas werecondensed into a four-neck flask fitted with an agitator, refluxcondenser, dropping funnel, thermometer, and a drying tube (filled withsolid KOH) which had been cooled in a dry ice/ethanol bath. The ammoniawas condensed into the flask via the drying tube. With good agitationand cooling, 60 g of a reaction product (perfluoroheptanonitrile), madein accordance with the technique described in Example 4 for conversionof a perfluoroacid to a nitrile, having the structure C₆F₁₃CN was addedslowly. After addition was completed, the temperature was allowed toslowly rise to ambient allowing the excess ammonia to evaporate. Theresulting white solid product was air dried to yield 62.0 g ofperfluoroheptanamide having the following formula (a yield of 98.5% witha m.p. at 75-76° C.).

Ultraviolet spectroscopy showed a characteristic amidine absorption bandat 212 nm, for the group

and an extinction coefficient, ε=6098.

EXAMPLE 5

In this example, various perfluoroelastomeric compositions were preparedusing as a base perfluoroelastomer, tetrapolymers prepared by batchwisepolymerization in aqueous emulsion as described in detail in WO00/08076, incorporated herein by reference. The monomers in theterpolymer included tetrafluoroethylene, perfluoromethylvinyl ether andtwo curesite monomers, a secondary cyano curesite monomer,CF₂═CFO(CF₂)₃OCF(CF₃)CN and a primary cyano curesite monomer,CF₂═CFOCF₂CF(CF₃)O(CF₂)₂CN. Polymerizations were conducted in an aqueousemulsion containing 1,1,2-trichloro-1,2,2-trifluoroethane using ammoniumpersulfate or ammonium persulfate/sodium sulfite redox intiation. Thesurfactant mixture included ammonium perfluoroheptanoate and ammoniumperfluorononanoate. The buffer used was dipotassium phosphate.Tetrapolymers were isolated by coagulation with magnesium chloride,washed with hot water and alcohol and dried at 60° C. The compositionwas determined by F¹⁹ NMR and elemental analysis for carbon andfluorine. Mooney viscosity was measured at 100° C. on a TechPro®viscTECH TPD-1585 viscometer. The following four tetrapolymers made inaccordance with the foregoing method and having the foregoingcomposition were used in the formulations made in accordance with theinvention:

-   -   Polymer A: redox type, 45 Mooney viscosity    -   Polymer B: non-redox, 65 Mooney viscosity    -   Polymer C: non-redox, 64 Mooney viscosity    -   Polymer D: non-redox, 93 Mooney viscosity    -   To the polymers noted above, used in these compositions, were        added various curatives and combinations of curatives,        including: perfluorosebacamidine and perfluorooctanamidine both        of which were from obtained from SynQuest Laboratories, Inc.,        Alachua, Fla., and perfluorosuberamidine and        perfluoroheptanamidine which were obtained from Federal State        Unitary Enterprise S.V. Lebedev Institute of Synthetic Rubber in        Russia. Perfluorocarbon ether oil was also used in various        compositions as an additive, and is available from DuPont        Specialty Chemicals, Wilmington, Delaware. Standard BOAP        (2,2-bis[3-amino-4-hydroxyphenol]hexafluoropropane) was        purchased from TCI America, Portland, Oreg. Both of the        diaminophenol curatives used in the compositions, Curatives A        and B were obtained from Federal State Unitary Enterprise S.V.        Lebedev Institute of Synthetic Rubber in Russia. Curatives A and        B each had the structure: (2,2,-bis[3-amino-4-hydroxylphenol]R).        In Curative A, R was —CF₂(OCF₂)₃OCF₃, Curative A had a melting        point of 120° C. and a molecular weight of 630 daltons. In        Curative B, R was —CF₂OCF₂CF₂(OCF₂)₂OCF₃ and Curative B had a        melting point of about 142 to 145° C. and a molecular weight of        680 daltons. Also used in the exemplary compositions herein is        carbon black, specifically Carbon Black N990.

Test specimens were made by mixing a tetrapolymer and the curatives toform a perfluoroelastomeric composition, and adding carbon black to thatcomposition, using a Brabender 100 g or 600 g internal mixer. Thecompounds, upon mixing, were shaped into O-ring preforms, molded to curethe performs into seals and then postcured into Size 214 O-rings inaccordance with the cure and postcure conditions noted in the Tablesbelow. The rings were tested for tensile properties using ASTM-D-412,Method B, and the following parameters were recorded: T_(B) (tensile atbreak in MPa); E_(B) (elongation at break in %); and M₁₀₀ (modulus at100% elongation in MPa). Compression set of O-ring samples wasdetermined in accordance with ASTM-D-395, Method B. Cure characteristicswere measured using a Monsanto MDR 2000 under the following conditions:Moving die frequency: 1.6667 Hz Oscillation amplitude: 0.5 deg arcTemperature: as indicated in Tables herein Sample size: disks of 1.6inch diameter, thickness of 0.17 inch and 9.5 g weight Duration of test:60 minutes

The following cure parameters were recorded: M_(H) (maximum torque levelin units of Nm); M_(L) (minimum torque level in unites of Nm); t_(s)2(minutes to 0.23 Nm rise above M_(L)); and t_(c)90 (minutes to 90% ofMH.

Tables 3 and 4 (Samples Nos. 1-12) are directed to use of novelcuratives, Curatives A and B, and to use of novel amidines andbisamidines as cure accelerators for those novel curatives as well asfor standard BOAP, and includes the use of BOAP alone as a comparativesample (Sample No. 11). The compositions include a tetrapolymer, one ofPolymers A-D, Carbon Black N990 and Fluorogard PCA. In Table 4, the curecharacteristics (except as noted) were MDR, 1 h@160° C. Table 3 includesthe formulations and Table 4 includes the data related to thoseformulations.

Table 5 includes data showing the effects of use of bisamidines andmonoamidines of the invention as curatives (Samples Nos. 13-19). Each ofthese compositions is based on Polymer A, and includes Fluorogard PCAand Carbon Black N990 as additives. In each of Samples 13-19, 100 phr ofPolymer A were mixed with 25 phr carbon black and 1.5 phr FluorogardPCA. The varying amounts of curatives are shown in Table 5 along withthe resulting data for each perfluoroelastomeric composition. In Table5, when the post cure sequence G is used, it represents increasing thetemperature from 25° C. to 94° C. over 1.5 h and then to 149° C. over 1h. The post cure is then held at 149° C. for 0.5 h and then furtherheated to 204° C. over 1 h and held at 204° C. for 18 h. The temperatureis then increased to 260° C. over 1 h and held at that temperature for18 h. The post cure is then cooled to 25° C. over 2 h.

Tables 6 and 7 include compositions and data, respectively, directed tothe effect of bisamidines and monoamidines as cure accelerators for BOAPcontaining perfluoroelastomeric compositions. In Samples Nos. 20-30,Polymers A, B and D compositions each including 100 phr of the polymer,25 phr Carbon Black N990, 1.5 phr Fluorogard PCA and varying amounts ofBOAP are cured with the amidines as indicated. The data demonstrate theacceleration affect of the amidine cure accelerators of the invention.TABLE 3 Sample 1 2 3 4 5 6 7 8 9 10 11* 12 Polymer A 100 Polymer B 100100 100 100 100 100 100 Polymer C 100 100 Polymer D 100 100 Carbon BlackN990 25 25 25 25 25 25 25 25  25  25  25  25 Fluorogard PCA 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5  1.5  1.5  1.5  1.5 BOAP  1^(¥)  1^(¥) Curative A1.8 1.8 1 1.5 2.5 3 3 4  2^(£) Curative B  1.9^(α) Pefluorooctanamidine1 1.5 1.5 1 1.5 2  1.25  1.25*Comparative Sample^(¥)2.27 mmol^(£)3.2 mmol^(α)2.8 mmol

TABLE 4 Sample 1^(β) 2^(β) 3 4 5 6 7 8 9^(β) 10 11*^(β) 12 M_(L) (lb-in)0.24 0.44 0.98 1.41 1.08 0.95 1.22 1.38 1.56 1.33 M_(L) (Nm) 0.03 0.050.11 0.16 0.12 0.11 0.14 0.16 0.18 0.15 0.11 0.44 M_(H) (lb-in) 14.3916.44 14.8 17.1 19.82 20.67 19.56 17.12 19.34 17.21 M_(H) (Nm) 1.61 1.861.67 1.93 2.24 2.34 2.21 1.93 2.19 1.94 4.7 4.4 t_(s)1 (min) 3.12 2.80.85 0.66 0.72 0.97 0.76 0.66 0.56 0.53 4.5 2.8 t_(s)2 (min) 4.54 4.151.29 0.93 1.03 1.56 1.11 0.95 0.71 0.67 t_(c)90 25.08 26.31 21.4 16.117.74 30.64 17.89 11.12 14.44 10.6 43.5 26 Mold cure 30/177 30/17720/160 16/160 17/160 30/160 18/160 12/160 12/177 8/177 cond. (min/° C.)Post cure 8/288/ 8/288/ 16/288/ 16/288/ 16/288/ 16/288/ 16/288/ 16/288/16/288/ 16/288/ cond. (h/°/C./ air air N₂ N₂ N₂ N₂ N₂ N₂ N₂ N₂ atm)T_(b) (psi) 1885 2169 1947 1219 1970 1990 1867 1877 1927 1701 T_(b)(MPa) 13 14.95 13.42 8.4 13.58 13.72 12.87 12.94 13.28 11.73 13.4 14.2E_(b) (%) 197 171 179 105 162 145 148 149 151 144 165 145 M₁₀₀ (psi) 621827 619 1056 884 1005 919 982 963 895 M₁₀₀ (MPa) 4.28 5.7 4.27 7.28 6.096.93 6.34 6.77 6.64 6.17 7.4 9.1 204° C., 29 20 23 13 9.2 10 11 16 70 h,25% deflection (%) 230° C., 70 h 16 14 (%)^(β)Cure characteristics (MDR, 1 h @ 177° C.)

TABLE 5 Sample 13 14 15 16 17 18 19 Perfluorosebacamidine 0.7 1. 1.251.5 Perfluorooctanamidine 1 2 3 M_(L) (lb-in) 0.74 1.52 1.83 2.22 0.470.73 0.84 M_(L) (Nm) 0.08 0.17 0.21 0.25 0.05 0.08 0.09 M_(H) (lb-in)7.33 9.21 10.32 11.63 5.88 8.71 9.97 M_(H) (Nm) 0.83 1.04 1.17 1.31 0.660.98 1.13 t_(s)2 (min) 1.46 0.72 0.61 0.47 1.1 0.69 0.6 t_(C)90 (min)14.23 14.12 14.57 12.88 11.02 9.44 10.21 mold cure cond. 30/177 30/17730/177 30/177 15/177 15/177 15/177 (min/° C.) post cure cond. (h/° C./ G8/288/N₂ 8/288/N₂ G 8/288/N₂ 8/288/N₂ 8/288/N₂ atm) T_(b) (psi) 12421306 1410 1524 962 1289 1521 T_(b) (MPa) 8.56 9 9.72 10.51 6.63 8.8910.49 E_(b) 100% 247 191 168 106 328 212 167 M₁₀₀ (psi) 357 406 498 1374270 379 597 M₁₀₀ (MPa) 2.46 2.8 3.43 9.47 1.86 2.61 4.12 204° C., 70 h(%) 11 17 19 11 63 40 24

TABLE 6 Sample 20* 21 22 23 24 25 26 27 28 29 30 Polymer A 100 100 100100 100 100 100 100 100 Polymer B 100 PolymerD 100 Carbon Black N990 2525 25 25 25 25 25 25 25 25 25 Fluorogard PCA 1.5 1.5 1.5 1.5 1.5 1.5 1.5BOAP 1 0.5 1 1 1 1 1 1.5 2 1.5 1.5 Perfluorosuberamidine 0.5 0.5Perfluorosebacamidine 0.25 0.75 Perfluorooctanamidine 1 1 1.25 1.25Perfluoroheptanamidine 1.25 1.25*Comparative Sample

TABLE 7 Sample 20* 21 22 23 24 25 26 27 28 29 30 M_(L) (lb-in) 0.39 0.950.46 1.4 0.33 0.72 0.47 0.36 0.72 1.61 M_(L) (Nm) 0.04 0.11 0.05 0.160.04 0.08 0.05 0.04 0.08 0.18 M_(H) (lb-in) 0.99 18 12.14 17.3 13.7 18.916 16.07 15.87 18.65 M_(H) (Nm) 0.11 2.03 1.37 1.95 1.55 2.14 1.81 1.821.79 2.11 t_(s)2 (min) 5.9 2.17 0.96 3.09 0.76 1.29 0.84 1.29 1.37 0.930.66 t_(C)90 (min) 21.3 20.9 15 25 17.1 18.41 18.33 16.3 16.05 12.687.28 Mold cure cond. 30/177 30/177 30/177 30/177 30/177 20/177 20/17715/177 15/177 15/177 15/177 (min/° C.) post cure cond G 8/288/ 16/233/8/288/ 8/288/ 8/288/ 16/288/ 16/288/ 16/288/ 16/288/ (h/° C./atm) air N₂N₂ air air N₂ N₂ N₂ N₂ T_(b) (psi) 2073 1354 1976 1659 1382 1878 16692158 1924 2009 2385 T_(b) (MPa) 14.29 9.33 13.62 11.44 9.53 12.95 11.5114.88 13.26 13.85 16.44 E_(b) (%) 136 243 135 190 138 195 143 169 142166 143 M₁₀₀ (Psi) 1180 348 1211 502 750 589 800 933 960 M₁₀₀ (MPa) 8.132.4 8.35 3.46 5.17 4.06 5.52 6.43 6.62 0.01 0.01 204° C., 70 h, 14 18%def.(%) 204° C., 70 h, 27 9 17 25% def.(%) 230° C., 70 h(%) 21 31 17 3120 260, 70 h, 18% 19 19 def.(%)

As can be seen from the data, the novel curatives of the Example providecomparable physical properties to standard use of BOAP, but due to thelow melting points and higher compatibility of the Curatives A and B andthe fast acting amidine curatives and accelerators, the curatives andaccelerators of the invention provide faster, more reliable curing ofthe perfluoropolymer to form the perfluoroelastomer.

EXAMPLE 6

Further Samples were prepared using polymers having the same monomers asused in Example 5, however, the polymers in this Example were mixturesof two different molecular weight chains Polymer B noted above inExample 5. The formulations are shown in Table 8 below. The polymerswere polymerized in the same manner and Mooney viscosity was measured at100° C. on a TechPro® viscTECH TPD-1585 viscometer. To the polymersnoted above, used in these compositions, were addedheptafluorobutyrylamidine as a curative and as a cure accelerator. Theheptafluorobutyrylamidine was obtained from SynQuest Laboratories, Inc.,Alachua, Fla. All other components are as described above in Example 5.

Test specimens were made by mixing a tetrapolymer and the curatives toform a perfluoroelastomeric composition, and adding carbon black to thatcomposition, using a Brabender internal mixer. The compounds, uponmixing, were shaped into O-ring preforms, molded to cure the performsinto seals and then postcured into Size 214 O-rings in accordance withthe cure and postcure conditions noted in Table 9 below. The rings weretested for tensile properties using ASTM-D-412, Method B, and thefollowing parameters were recorded: T_(B) (tensile at break in MPa);E_(B) (elongation at break in %); and M₁₀₀ (modulus at 100% elongationin MPa). Compression set of O-ring samples was determined in accordancewith ASTM-D-395, Method B. Cure characteristics were measured using aMonsanto MDR 2000 under the following conditions: Moving die frequency:1.6667 Hz Oscillation amplitude: 0.5 deg arc Temperature: as indicatedin Tables herein Sample size: disks of 1.6 inch diameter, thickness of0.17 inch and 9.5 g weight Duration of test: 60 minutes

Table 9 includes the data directed to the effect of the monoamidinenoted as a curative for a perfluoroelastomeric composition and as a cureaccelerator for a BOAP-containing perfluoroelastomeric composition. InSamples Nos. 31-34, the Polymer B compositions each included 100 phr ofpolymer and 25 phr Carbon Black N990 and BOAP as noted in Table 8 whichwere cured and/or accelerated with the amidine as indicated. Theinformation in Table 8 are indicated in parts per hundred. Sample 31represents the control. In Table 9, in compression set data, thepercentage measurement indicates percentage deflection and the data isbased on post cured samples. The data demonstrate the curative andacceleration affect of the amidine cure accelerators of the invention.TABLE 8 Sample 31* 32 33 34 Polymer B (110 Mooney 75 Viscosity) PolymerB (24 Mooney 25 25 25 25 Viscosity) Polymer B (114 Mooney 75 75 75Viscosity) Carbon Black N990 25 25 25 25 Heptafluorobutyrylamidine 1.540.64 0.64 BOAP 1.5 1.5*Control

TABLE 9 Sample 31* 32 33 34 meq amidine/ 0 7.26 3.03   3.03 100 gpolymer M_(L) (lb-in) 0.80 3.05 1.65   1.22 M_(H) (lb-in) 15.85 13.9716.76   8.76 t_(s)2 (min) 5.68 0.50 0.69   0.76 t_(c)90 25.94 4.08 11.23  6.02 Mold cure cond. 30/177   15/177   15/177   15/177 (min/° C.) Postcure cond. (h/° C./ 24/288/N₂ 24/288/N₂ 24/288/N₂ 24/288/N₂ atm) T_(b)(psi) 3171 2003 2375 1756 E_(b)(%) 122 121 117  225 M₁₀₀ (psi) 2393 14271924  625^(£) Hardness 84 78 84  78 Durometer M Compression Set 10.007.69 12.00  32.00 204° C./70 h/18% Compression Set 9.99 8.33 8.57  28.57204° C./70 h/25% Compression Set 12.00 3.84 8.00  36.00 230° C./70 h/18%Compression Set 11.42 8.33 8.57  34.28 230° C./70 h/25%*Control

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

1. A method for making a curative, comprising (a) reacting an organicalkylacid with an alcohol to form an alkylester; (b) reacting the alkylester with ammonia to form an alkylcarboxyamide; (c) reacting thealkylcarboxyamide with dehydrating agent to form an alkyl nitrile; and(d) reacting the alkyl nitrile with at least one of ammonia or an amineto form a curative, wherein the curative is capable of curing oraccelerating the cure of a perfluoroelastomeric composition.
 2. Themethod according to claim 1, wherein the perfluoroelastomericcomposition comprises at least one cyano curesite monomer.
 3. The methodaccording to claim 1, wherein the curative is perfluoroheptanamidine. 4.The method according to claim 1, wherein the alkyl nitrile is added toan excess of the at least one of ammonia or amine.
 5. The methodaccording to claim 4, wherein the at least one of ammonia or amine isliquid ammonia and the excess of the liquid ammonia is ten fold.
 6. Amethod for making a bisaminophenol-based curative, comprising: (a)reacting a perfluoroacyl fluoride with potassium fluoride to form apotassium alcoholate reaction product; (b) reacting the potassiumalcoholate reaction product with a perfluoroallylfluorosulfate to form aperfluoroallyl ether; (c) reacting the perfluoroallyl ether with anoxidizing agent to form a perfluoroglycidyl ether; (d) reacting theperfluoroglycidyl ether with aluminum chloride in a fluorinated solventto isomerize an epoxide group on the perfluoroglycidyl ether to aketone; (e) reacting the ketone group with phenol in the presence ofhydrogen fluoride to form a bisphenol-based compound; and (f) nitrationof the bisphenol-based compound to give a bisnitrophenol-based compound;and (g) reduction of the bisnitrophenol-based compound to form abisaminophenol curative, wherein the bisaminophenol-based curative iscapable of curing a perfluoroelastomeric composition.
 7. The methodaccording to claim 6, wherein the perfluoroelastomeric compositioncomprises at least one cyano curesite monomer.
 8. The method accordingto claim 6, wherein the bisphenyl-based curative is a substitutedbisaminophenyl-based curative which has formula (III):

wherein Z is an amino, sulfhydryl, or hydroxyl group; and A is selectedfrom the group consisting of unsubstituted and substituted and branchedand straight chain carbon-based groups, wherein the carbon-based groupsare selected from the group consisting of perfluoroalkyl andperfluoralkoxy groups of from 1 to about 22 carbon atoms.
 9. The methodaccording to claim 8, wherein A comprises from 3 to 10 carbon atoms. 10.A substituted bisaminophenyl-based curative for perfluoroelastomershaving cyano-group containing curesite monomers, wherein thebisaminophenyl-based curative is a substituted bisaminophenyl-basedcurative which has formula (IIIa):

wherein R³ is a carbon atom; Z is an amino, sulfhydryl, or hydroxylgroup; J is formula (IV):

and A is selected from the group consisting of unsubstituted andsubstituted and branched and straight chain carbon-based groups, whereinthe carbon-based groups are selected from the group consisting ofperfluoroalkyl and perfluoroalkoxy groups of from 1 to about 22 carbonatoms.
 11. A perfluoroelastomeric composition comprising abisaminophenyl-based curative for perfluoroelastomers having cyano-groupcontaining curesite monomers, wherein the curative is a substitutedbisaminophenyl-based curative which has formula (IIIa):

wherein R³ is a carbon atom; Z is an amino, sulfhydryl, or hydroxylgroup; J is formula (IV):

and A is selected from the group consisting of unsubstituted andsubstituted and branched and straight chain carbon-based groups, whereinthe carbon-based groups are selected from the group consisting ofperfluoroalkyl and perfluoroalkoxy groups of from 1 to about 22 carbonatoms.
 12. The composition according to claim 11, wherein thecomposition further comprises a cure accelerator selected from the groupconsisting of a monoamidine-based cure accelerator, a bisamidine-basedcure accelerator and combinations thereof.